Genomic sequencing can be used to obtain information in a wide variety of biomedical contexts, including diagnostics, prognostics, biotechnology, and forensic biology. Sequencing may involve basic methods including Maxam-Gilbert sequencing and chain-termination methods, or de novo sequencing methods including shotgun sequencing and bridge PCR, or next-generation methods including polony sequencing, 454 pyrosequencing, Illumina sequencing, SOLiD sequencing, Ion Torrent semiconductor sequencing, HeliScope single molecule sequencing, SMRT® sequencing, and others. For most sequencing applications, a sample such as a nucleic acid sample is processed prior to introduction to a sequencing machine. A sample may be processed, for example, by amplification or by attaching a unique identifier. Often unique identifiers are used to identify the origin of a particular sample.